SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '4d0b4bf31d67ae75caee948c69db3618686628fd2c007b0dc6b30795605acb77' 
  AND token = '6CtkuWN5x5qK+fbHjS0bDvsmwch313/dPcS+TPT6OA8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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