SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e1f5776382c247285bef523d5a6441fb45adcd4843545b9a264883f2a877c6ec' 
  AND token = '1j+bzi/qwKzqWdGsQesurdMoQhDL4FwSQXLlUo2+vrc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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