SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43ffc99930592055d4a5073568b9f51886a4bcd5e911746ea6d9ad94db581b05' 
  AND token = '0eLFCtNipAPRctG6/cRPWjyFOptrZnd+Uw0UHJhoqg4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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