SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d1c3dec87228c3b046f30b5bb30b4a9a31ef8fa73c2baa16e5260bde14b2f73' 
  AND token = 'kXlRrmoFVUOovmwJ6BhQ09WzyJaiNdDGAyLrL+KWDtY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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