SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e28df9059413cfb0ed59685c617542d4efff94dcf5a5f3e54f02727bd4db910b' 
  AND token = '9YnujG+thWsbFPpCtldhXo+VTey4eBdjH2tQipLR/FU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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