SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7686935e7dc7419765abd55dbc5abb1821e55b6d36fa2435d8a059bdce846fe' 
  AND token = 'Mc77UlLkWGgP+X/Ct6pESKO5nwryaECNQpeoRAYuAak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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