SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '442490e0f126c5110765579dab5ee3cde4ce0e9599b845dd9c2365e37989c246' 
  AND token = 'YhFkpRcE/nrZxsEAVXon6mgEBPfcWepwEwaPr8k/pQ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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