SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ea6839f1e85bd34725754b0195a687d01680db855747bb6d4a543b0619756f0' 
  AND token = 'ilq+Tnh0ArOR1zMxnZ4VxzLMnNyMipkPHf6cLvO7UQE=' 
  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"
    }
  }
}