SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27b17544f00a15aff31e6a2888459f184c75b4f1495c2173fbca0c51c277e2b2' 
  AND token = 'jBcZM3xhIKBqdG9GvPwK3Z/LIvPla0vCYS78+ZOk8KA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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