SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '343dd16c92e1463f8491b6e7046015e455dc6f3a0063a5833806f58241b141c5' 
  AND token = 'evYZshHZhLrDgQ6+U0saWdMdbuPqlfJ361ipMsgpfA0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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