SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a37c53108731056b2ca35fcf1bc9af2e3beaa408927a46340790ff9851b3900e' 
  AND token = '2OKzW4FtlYvenAPtj2FItM8G6VToNYPmbvsGJTYhd2Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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