SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '712d7e2a1e756ce4ab3411c3542e9bef3280b6e04d08acb578fa77837210dc97' 
  AND token = 'UfoixNgjRorfhXLxyBnPIOhy3UUR+5wV5BiDd2MgmTc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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