SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e935ff0864715abae50439b550e5425697c79baba5a3e1dd931ce088fd9d17d' 
  AND token = 'u5NMoUJ08LITsz17DjVmlWm42QDw+eMhsKM/vTZkIrg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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