SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '355c82f889f5f53e91058416e6175b82413357ad8ec0a44194fe4039c27fddf0' 
  AND token = 'nYunSYfNEftQjirX1WhledUXYMslpRmoqvBriKfEFHw=' 
  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"
    }
  }
}