SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9675975dbbaece8179390352a68d92b07a368ece04dce31c6aabe09dbf15a9f' 
  AND token = '+ZVvKd3kePuefoXcn+Mt76rx+FWBRtYGgMcmql55LBM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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