SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d4e87b3b9fc61b14bb54b5ba254e4c8c84487b55befc8091e6e0533515a3afd' 
  AND token = 'M8lalO1ZYzEckGh/4iW5J7NYhg96mwvj/lFDIqvQVVE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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