SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4db5f28b22e8e3a817251f923e4877413bfae51d7cec793ed9bffc52da02e09' 
  AND token = 'hLtQTHqMj8BUhS6sMaW90pQztcW4cFBYYYyEME05bzY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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