SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bf17569187cf81500523d9bb0b5b5d861882f2614e9e7c361d1a6fbdbc7382b' 
  AND token = 'x2+Y7MGCEANfjCjwPvzSU8XBrsZP9hDwF0USZB4rN2A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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