SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c7f3c660aecb0d93dabd3cfb30f60567004fdaaa8840c1f97d27783d2242e2a' 
  AND token = 'EOKuXPXzIBveMO3V44ol6qKdEYx7aZqmCM6VNdYM+wc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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