SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96d9814e36dab509944f26ea704cca6f377e1c3d5fb8a83f1b1e3aa60fa5103d' 
  AND token = '1tglkQCTgxWK+iyUT2Rx8DQiYqrzeK1QLlBQmOtWTtY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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