SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '494dd3cde8419be303ac0139f02a0c342879294632919ae0421c5a250b8770be' 
  AND token = 'SR1Oi0gKUTph3RidkArb1/oZJmsXIyXN4TMX/coAd98=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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