SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e1eddb86f0442051d745eee1651679c6b91aabc62621340192185e6390dfaff9' 
  AND token = 'rqBqKPiRK9RhStMn620AnGkQ1g+NAmZyymzf6usjAfc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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