SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8bf28b0cea6696924a1d75711434ab39cdba99bba5903459692a9b63df4dda0a' 
  AND token = 'HyPyernDirtIo00hMjQu5mYjUrtgYbb9Ay4zTL5JI+M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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