SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e3133b7da80ab04a240ba6c4674452e664424b297a146e9723344218b278886' 
  AND token = 'QruWiMaxtFKZ93LPVAzsrXp5byL7NUw2tLIeOtssPz4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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