SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29620c38e84f3e9d8c36b415aed5a37519d7acefef5d8d2be1c0ec4525472d35' 
  AND token = '4K2RJZ1H0YnZyKyZl2Ck1ClMOYgT1JNmDTJO9gQOkvw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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