SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5183403d74d29b8bad664a0297bca0f16dda2335e8083c58fd52e8c425a9b9ac' 
  AND token = 'c/qTMhtQ9I2+iKEWC6G5NKQVwSpguqvaSb95vq0h4wg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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