SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb570e90f6b7896c4351e5844d10c8c21a562981c163e44d98c8363d04ee6852' 
  AND token = 'zCw2LMA/HmE3PZplH9R50RNF0xYbrx7QPHwkgzBh+3E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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