SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8540dc292a7b9d909e8d3354be90415186ed0e061d4999c751f8fe6f110ce432' 
  AND token = 'ZqaZWqqSqn5ZapDSZBIg++YfAMLG+/wWltIXqELtDr8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}