SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b3941def7f0e1d0fa03faeaf7188b0d8ee8943df970e683b24cdbb554795ea5b' 
  AND token = 'hNsmRIJzuETcB/wwqYeaSDyYSnH/awTfOXbA7oqSrKA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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