SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73a8916fe9070171054da7bb2c238a291d940ae5454ce84d7e1816bcf3771bbc' 
  AND token = 'P7mgTyD2lsqIi1+ZeMsPqmVOR8UvggKE2WLf82gMD6Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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