SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfb983fe684d3315230ec317ab16f555ccdd6cce0afd1a19ff106743da5ec01c' 
  AND token = 'TLJao4BhsScd3YZncResUHHxXySH3g1EsrxzzRyfYpc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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