SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83632d9740b92762c6733f6490442d618ea6b339c51ca2634ddb5ce00dbd576a' 
  AND token = 'pRYshQlS9+DQO8cGAfEVbYjUIJHBXIzT/sUCjEjf+kI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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