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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c75cdc31daf92507a7e3e83700c522de7d8d21e8b34eaed658bdf2ed00b83f79' 
  AND token = '7dTih01Fj2T1l5mxfzv9kazLaC4PZQipSGPD5sso+yY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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