SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7abc02f6aa92856dadb4e5396897d3d5fb3fd929d9a86a177015cdfb45d3954d' 
  AND token = 'mrYlUGBdoH3gYqq+td7KbJq9IzVvJaqXXNcEt6iNRK8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00067

JSON explain

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