SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '520393ee0d01bdb07f9cb6a320af1a92c77467858f808fb74bbee06ef40b592a' 
  AND token = 'P8WJmPSDkWesAiKLGSDJJYa1MYl+WfUUMhXfaIBDn2k=' 
  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"
    }
  }
}