SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57ad30c2e40919ec6c9e3cd063926da313c975761e13a2b2919f51dd0b48ae43' 
  AND token = 'zBkO9KKe6swHOusiBoP4w6HzpF7AJBtW4msLEbp15qg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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