SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e575321ccd5c69fb270f5e2db9a50d1ecfe0ff1596bea0effb82a37bd622c0c3' 
  AND token = 'w15VVeUFjzY2pd6nhov8fSqEWdoV19WPwh393L23nv8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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