SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75ddf6a0309d54aaceab1912bd63c39baefab3fe398823d357309b68c148ba93' 
  AND token = 'UDctnyCz0/SF9d3HcLC3z566ylhjXZnWtoAMnLAcmlY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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