SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eaf36335f62a98b5c7f60338e65368e4b028db86ea33df7fc253bdea3d695eaf' 
  AND token = 'cmspCXFgTG+ZtCftZ0BXAk+qDoC2XVxtEaLL+dlGlBg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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