SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b53aef58d63ff486a94b4a6fcbe231bf560caee3b4a6e261d8813c914450f655' 
  AND token = 'nbe3ceqUD8JRyeJO+kVTBJrPqc2GIr/gGNQJvcaR4p0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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