SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8506f2136298875c7d0171aa495cbcffa8be8fb3e38f194ef26953ae92ce690d' 
  AND token = 'x0aZ+tRiKlY/zRz1yt8CCpqWIKmesKfgMu1wQd2c7wE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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