SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29358839937a716b197bf39596f2b64bceef733c667d924c2aee8ee99c794819' 
  AND token = 'UXROye0Jue63hKtKHofnGtqNmHNmIzAo4Vz+F3RuWlg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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