SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '394b8383fc3726887f7213f9bf52915c0c44d39201acef893cc0536d5a8ae685' 
  AND token = 'kBfZmqsQfaAKsmiu2kssad+3a41QkWsltrRH5BJhCX0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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