SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5fcfbb67b4abd3168bf27c30736c654bcc21331079aa65e7bff4c2157559e5d6' 
  AND token = 'rZSTfMXFhwGEt/YY+ETm9dvN9+CVrCR5B/xiD5hL+lQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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