SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b98fbac8437d28d481bb0b70de239eaf0371fd26b189322fb42586796af0a396' 
  AND token = 'cndFVhrJAuzRQJLpErGq8RDHid3DoCxCnURX5YrvUpg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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