SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f3fc222c94772992218ba562f9760e424e77a8b315553e89d4511beeaaed091' 
  AND token = 'IV/jdDegucPoNxKLxzjCSxVnPHIT6Bm+gie3X88czUA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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