SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '251e9fc5f0ba1267f10fc06de2a7afd441624d3e4b48703ceabd073fc7255335' 
  AND token = 'CQtQV2aNz7sMHlaAF/NJm+wNqQULzJVlhHRwtcvnipU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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