SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8fad5795de3e90cfb72e2cc1cad5276fe175f85acbe8252935bdb92df02c357' 
  AND token = 'jqDAxOQnwNkuXE78cmJu3flgRJ5t4U851IsZlYn7Jzs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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