SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '996603aae6c52859a29cb704ecc5c822fd419395f04e4e4dfc1c6475c2942c98' 
  AND token = 'Gj+MDdGSVdRYVEevIgCL89VmGMG0zTsYlI+MlY9lGDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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