SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75f1a680ab2b6d4ad192de764f2989d02c495296926d5541110e9bbd221b30d8' 
  AND token = '2aUP0+KvvArKAYbw3FsYh82ebqBssnxKSZy1SfC/CBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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