SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f1f9a1b91fbc4e21873b7d850f1ac846148907b85b14ac2f83550fcee3ad4439' 
  AND token = 'OwIhf1kKqbfKMgtYU3pahXVIK/b/5yEtyupw9JZY7Ic=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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