SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92845b5867fc162f12824703b97cc285331e825eaaa448c07f6d61ec99793da9' 
  AND token = '7ktT8SK1XYSslW8pxBbhz2Vfxe/bEEFnUEJwbdL/uv0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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