SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1af6dd70ef3e28628047002b20d499dcbb423280cf86a131321b9e356de21c3e' 
  AND token = 'SS4Lsy/FyTvdciFC8G7k5EFdBa4HxPpDqcwIA6iMVIw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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