SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '75799dd7eb3681bbb8d6057d314a60de67ac1977cf479b8e7a39d358fd869dfa' 
  AND token = 'OpjV6AtXAQsKyVu/psLyeStJhyKiBkehvemoMoQHxME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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