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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '137c2f7d78879fd04e4ed5bbe340a2e701805edd85d8d1ea9f047867a8a65389' 
  AND token = '2pj7nD/a7cWG6ilEMSfZUojkcnE+SOoayZhcQ1AzRMM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}