SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0e6498018018666f61628da51cc22d67a65ffb9ee830336d6b5a952890b7252' 
  AND token = 'KhzFJszmEsWgbjHNdWnhtjHF0QamcRMOhIJfxoTXU/0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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