SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b62f88b0a3d884acaaf85e572657b8eecd9f42bd94d67603bbeddbe013d50473' 
  AND token = 'ZZrDsEUYKvRD112PH+1uTfTg/HpaOGTLH19MY+sfvC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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