SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab5e1201f9fc49a35a0b781a837eb1d6084a680f8803e71703e5a4093e248658' 
  AND token = '18rIaaP6VTfrlkchI42uF7X8FDeUV0nDrf1wQd1IiZ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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