SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf6b3d16a63c543226ab82111bf54c11c5e0e3158efdf470895a53297bd2d6ef' 
  AND token = 'lBYFYrdXqk+rIr/k3UsJaGAJTBTl4CwfsVWlDPhmK00=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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