SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '900fca90dc3fc4609c462887525e572b98191108620c624fdbcbe9667bf2ebcf' 
  AND token = 'kZgjvDA1wohy9Nifl73Eyvq5wJcvhc0JxEESNHeIkyI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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