SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f031a4ea375861e5186db7101b86646c042fc5a616b8ef27f8d85c7b219e377' 
  AND token = '4OUsePVJLOTLr45U/wzazd79qJGRm4KuiO5/+9vZhF0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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