SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e98bf9d7257bed811a54f9b647d8e6d1567e36f94978d03aca9fe609b1a711b8' 
  AND token = 'U2PQU0Fraj7cYVloVx2ZtH2XJAh04+mCMvZ9WB4yThU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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