SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '7c54943f894001b530904563cb0bc775a260c9e043577a03fed78a14e9a3397c' 
  AND token = '8wa6QgZbFrWlZf+o7p8Sj1/AN8NUA6MUGa/hNxemkRo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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