SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '796bc9bf86e616e95e5a0a7c3b87451670f2239dd9e2b3a8949367e675008112' 
  AND token = 'b++4SxzK5C7UEf5OYzw3upXXIB6EwrYWvRUZKZxmyj4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}