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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c3b60d84fc646523bf252c02d75aaaa5d6019d6313f5ed8f4451acef1a54983' 
  AND token = 'ajSrUTxhU+9ve5HOIDKRnomNw/iWHBvr2o94Pfle9Ok=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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