SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fea2c404b548f5364615d2da9786345885e5fc346ce002411be5f353fcb55e49' 
  AND token = 'QPThW0BtiDK81E93OUbPUOnovTTgKcI5638vLegtcMc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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