SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a769281b5834ad4f0e9c7900e59c2b247b24b47c8c48fe51d115bf3af28e56cc' 
  AND token = '6S7bHhbzO0phxt2K5rx8hzNmsZXYHWQ+7GgvBAkSqp4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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