SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4e6e489ad6049b71a090462a649c5ab15bfda76cf6a8eea5333f03599825b091' 
  AND token = 'G5eDw5Txrn7kQmGlxLEBh564g0moQIPdYNgDtK18SKI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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