SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c3af892c559aad3540b57b496287a595c02e4c62f843c497ced82b5d56c1016' 
  AND token = '4HwqTxDyO8JDEKx/UX+8meLBQXfRoiIT1Z8VS0bLGQg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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