SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7b9235cc222e2f8c7c1c6bbe309460dc55aac8a81eda05b57af94ed9c83f95f' 
  AND token = 'QB4L7cLif+1hJjPoEKkLsepWvgnZ52mdG9vo6nhRYH4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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