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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a61b8f96b3a30e6f434ccdefb66b7b31fea47eb0e016c7753cae44ed1bb48b6a' 
  AND token = 'ekmearMEipZLzhN1VuyDAWUiMBeNsPpmN4V9Zz/olaQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00078

JSON explain

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