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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4b8942bb49f9cdd82f23ce380aedfa3099bb3d27bd2dd355b4d08781fac2b2f' 
  AND token = 'gjDwaT6irM7Arr9u+ukpdV/AgFGKoljWbpxbXTZk4UM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}