SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b26c92d1499fe504c63ea08e6ef9f0c6d4119b15c11bedab78d66ea13b46eb89' 
  AND token = 'wEQY3KQWIw6XnOOAJUW3qukPFVWbuUjfzty++BuAIY8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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