SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3cbda1670298de7ca3021133f7acdd175d556cf7da5be0af1598af2a755a0c4a' 
  AND token = 'my+jZEv7rXKkXMcJHYeqYN0AVnd3PiUCK65rcidwfAE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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