SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90a14008097ef4573b5f9269f7d6610eb31c1dc68e808cee5b7754a1f2dbb3a9' 
  AND token = '9d2ZCc+h+K0IEsIuHHD7XMK6HrZY9PRf3ZCJm4Vppeg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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