SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '637fc9a90b64873d2dfb52675ebfc3e3be56cb3bdc248d356f04f592e55c1dd0' 
  AND token = 'GFUfX82ujaJIWwmhN3eI1fDj1sIl1bWJe3viBtPdJrY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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