SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8537bce2e10268326dcb89745aa847a6dfb39d256fc4d1abe8125f1c027a597a' 
  AND token = 'IY3EKYXIiVG+EGM/Jf5EKP2ddzlI5zEZepK1F75d8qA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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