SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7922c135f38e6c1f0c34b93c77faca1c7be6a3e016fed59b9845e77a037af1e2' 
  AND token = 'pN8ZOhJv824rnv+mweybjoqp4Q23uGxQ2sn76LM+JBo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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