SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0d40fdc7ef5084af94da560a92b30350806e6c368b299a1edf9f6363faf961a9' 
  AND token = 'pOg0hBPgjH4MpueVFtWzGGBVe3p68kLCCWcFFYIXnNY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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