SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fbe316cf80dc9799b4ccaab13f77e8067135c8782edf1557837319ded9b16f0' 
  AND token = 'WZSsQBkwkkmpXytWYh1mzn0aojZbCUl4F5umLLlmp/I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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