SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5f603d6017c235a5e073fc329c0a562cc722f01493af09605ed979e4f8880620' 
  AND token = 'xi57xF45h5ulGAZx1EQ2/9nEKMfosgbast5cM9eAG+w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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