SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b1d0dfcee58dd36d3838a300d02fda17133938eb578cd0bee8ba433f2752fbb' 
  AND token = 'MjaB6IbKyuEUzxjEQGDOzbdIO5KmNIgGDmAZQy3oTRs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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