SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f2f8f5c2a6a35e23bbe7e16c767f3575e21b47300aed97642654eb71f86fbd2' 
  AND token = 'h5WBcuvetCpIFfRLTPMdjQgI+xVdnwdPYcjCzn+gf5o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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