SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a5475e870b19134a2251c298311b77920bdb83ee9a9e9633c906525f00ed4279' 
  AND token = 'ZsJSxohBzX0G71Hwchjs9o6RXFAivyElPO4F2PasgKU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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