SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb1cd2cb017c231b31061cafeb584dacd68168d81e669e91b3f118628c9762b3' 
  AND token = 'PnZLh/s5jQkIQdGwHGBGLNgAtwewWjrAZdtteULaQMA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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